Conventionally, as the ion exchanger of this kind, there is one using a sintered body formed by sintering ionic exchange resin and thermoplastic resin (see patent document 1 for example).
The ion exchanger disclosed in patent document 1 is formed by sintering and coupling such that ionic exchange resin particles exists in porous matrix of thermoplastic resin. Therefore, as the amount of ionic exchange resin charged into the sintered body is greater, the ion exchange capacity becomes greater.
As a producing method of ion exchanger formed by sintering and coupling, there is known a method of coupling functional group by graft polymerization (see patent document 2 for example).
In the producing method of ion exchanger disclosed in patent document 2, cross linked body layer made of graft polymer chain is formed on sintered body surface of polyolefin resin particles, and functional group such as ion exchange group and chelate group is coupled to graft polymer chain, thereby suppressing elution of impurities.
As a water treatment device which removes hardness component in liquid to obtain soft water by ion exchanger, and automatically carries out regeneration processing of the ion exchanger, there is known such a method that textured film having textured structure in which peak and valley are alternately placed on a surface is used as positive ion exchange layer and negative ion exchange layer, and ion exchanger in which the textured films are laminated is used to remove hardness component in water (see patent document 3 for example).
FIG. 10 is a schematic diagram showing outline structure of the textured film and electrochemical cell disclosed in patent document 3.
As shown in FIG. 10, the textured film 105 disclosed in patent document 3 includes a positive ion exchange layer 101 and an negative ion exchange layer 102 which is adjacent to the positive ion exchange layer 101, and a surface of the textured film 105 has textured structure in which peaks 103 and valleys 104 are alternately placed at distances from one another. Since a surface area of the film is increased by the peaks 103 and the valleys 104 formed on the textured film 105, when water including hardness component is supplied to the textured film 105, absorption speed of hardness component can be increased.
Further, patent document 3 discloses electrochemical cell in which an electrode 107 and an electrode 108 are placed on both sides of the textured film 105. According to the electrochemical cell disclosed in patent document 3, if voltage is applied to both the electrodes 107 and 108 in the presence of water, water is disassociated at an interface 109 between the positive ion exchange layer 101 and the negative ion exchange layer 102, and H+ and OH− are produced. The H+ and OH− are positive ion and negative ion absorbed by the positive ion exchange layer 101 and the negative ion exchange layer 102 are replaced, the positive ion exchange layer 101 and the negative ion exchange layer 102 can be regenerated, and the ion exchanger can repeatedly be used.